1. Field of the Invention
The present invention relates generally to couplers for flexible corrugated pipes having structures in which peak portions and valley portions are repeatedly formed and, more particularly, to a coupler for corrugated pipes which is constructed such that a corrugated pipe can be easily coupled to the coupler only by inserting the corrugated pipe into the coupler and tightening a cap nut over a coupling base.
2. Description of the Related Art
A representative example of conventional couplers for corrugated pipes was proposed in U.S. Pat. No. 4,630,850. This coupler includes a coupling base which has an external thread on the outer surface thereof, a cap nut which is threaded over the external thread of the coupling base, and a sleeve which has a protrusion which is inserted into a corresponding valley portion of a corrugated pipe.
The sleeve has an opening in the outer surface thereof, so that when the corrugated pipe is coupled to the sleeve, the protrusion of the sleeve is expanded in diameter by a peak portion of the corrugated pipe and is then inserted into a corresponding valley portion of the corrugated pipe.
Furthermore, in the conventional technique, an embodiment in which a sleeve comprises a pair of semicircular members was disclosed. The above structure of this embodiment is to achieve the purpose of being able to elastically insert a protrusion of the sleeve into a corresponding valley portion of the corrugated pipe.
In the conventional coupler having the above-mentioned construction, to couple the corrugated pipe to the coupler, the cap nut is separated from the coupling base, and only the cap nut is fitted over the corrugated pipe. Thereafter, the sleeve is coupled to the corrugated pipe and inserted into the cap nut. Subsequently, the cap nut is threaded over the coupling base, thus completing the coupling of the corrugated pipe to the coupler. However, the many processes make the coupling work complex. In addition, because the coupling base, the cap nut, and the sleeve are individually handled, there is the possibility of loss.